Mineral oil compositions and methods of suppressing foaming in oils



Patented Mar. 26, 1946 U N RTE s'mrss MINERAL OIL COIWPOSITIONS ANDMETH- ODS F SUPPRESSING FOAMING IN OILS Herschel G. Smith, Wallingford,and Troy L. Cantrell, Lansdowne, Pa., assignors to Gulf Oil 4Corporation, Pittsburgh, Pa., a corporation of Pennsylvania 7 NoDrawing. Application March 19, 1943,

Serial No. 419,794

2 Claims.

This invention relates to mineral oil compositions and methods ofsuppressing foaming in oils.

In lubricating machinery with oils, and in handling oils as by pumping,conditions are often such that the oil is subjected to violent agitationin the presence of air; conditions such as to produce foam or froth. Insome cases foaming or frothing is quite objectionable. For example, inlubricating automobile gearing (in the gear box, and rear axle) foamingproduced by the churning of the gears gives rise to excessive leakageand loss oflubricant past retainer rings, etc. More-'- over, foamingseriously interferes with the proper functioning of the oil. Automobilegears such as those used in transmission and differential gearassemblies often operate at very high speeds, as well as under hightooth pressures; therefore they require a very good lubricant to preventor retard excessive wear due to metal-to-metal contact, and foaming isundesirable. 'I'h'e lubricants employed are viscous oils, oftencontaining a so-called extreme pressure agent to assist in maintainingan oil film between the teeth; sulfurized sperm oilbeing especiallygood. If the lubricant contains air dispersed through it, it lacksproper film forming properties. Also in reduction gears, particularlyherringbone gears, oil aerofoam is undesirable. Moreover foaming oil ismuch less effective to conduct heat away from the working zone. Thesedimculties are often aggravated by the fact that some extreme pressureagents present in the oil actually increase the foaming characteristicsof the oil composition.

Foaming is also objectionable in other situations; for example, incompounding oils with extreme pressureagents and other additives, anoperation involving thorough agitation. Nearly all petroleum oils foamto some extent under violent agitation, The more viscous the oil, the

- greater the amount of foam and the longer it are such as to causefoaming and loss of oil entrained in the gas removed. This loss of oilis objectionable. Moreover, as an airplane climbs to high altitudes, thetemperature and pressure of the oil may be decreased, conditions whichpromote foaming tendencies.

Among the objects ofour invention are the provision of a method wherebyfoaming or frothing of oils as described is suppressed; and theprovision of gear lubricants and other lubricati compositions which arecharacterized by freedom from tendency to foam or froth even undersevere conditions.

We have discovered that foaming of petroleum oils can be suppressed orprevented by incorporating in the oil a small proportion of certainorganic ammonium salts of acid octyl phosphate esters. These anti-foamagents are organic ammonium phosphates having the following formula:

wherein R represents an alkyl group containing 1 to 18 carbon atoms andX represents an organic ammonium group derived from a terti y amineselected from the class consisting of heterocyclic' nitrogen bases anddialkyl aryl amines.

That is, our new anti-foam agents are addition salts of said amines andaciddialkyl phosphate esters wherein at least one of said alkyl groupsis an octyl group. In fact, they can be readily prepared by reactingeither heterocyclic nitrogen bases or dialkyl aryl amines with variousacid octyl phosphate esters having the formula:

wherein R represents an alkyl group containing 1 to 18 carbon atoms,including both straightchain and branch-chain alkyl groups. Such methodsof preparing these anti-foam agents are further illustrated post. Theseorganic am-. monium phosphates may also be prepared by other suitablemethods.

For example, dimethylaniline dioctyl phosphate is a very good foaminhibitor. The addition salts of acid dioctyl phosphate with otherdialkylanilines are also useful anti-foam agents.

Likewise, dialkyl-aniline salts of other acid phosphate esterscontaining an octyl group and another alkyl group, such as methyl,ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, yl, isoamyland the like, are also efiective ti-ioam agents for the presentpurposes. Those containing branch-chain alkyl groups are very effectivefoam inhibitors. i

For example, a small proportion or ethyl aniline isoamyl octyl phosphateis most efiective. Again, the diethylaniline salt of isoamyl octylphosphate is also an excellent foam bitor. In our copending applicationSerial No. d53,58, filed August 3, 1942, we have specific claimed :11:proved mineral oil comtions contng the dimethylaniline and diethylesalts of isoal octyl phosphate, as the anti-roam agent. l 'he presentapplication is a continuation-impart or said prior application SerialNo. dSSABt.

In general, the organic ammonium phosphates having the formula Iii-MR;

. phosphate having the following formula t i i being particularlyefiective and advantageous as described in said prior application SerialNo. 453,458. As a class'these ti foam agents are useful in the practiceof the present invention.

Further, the addition salts of said acid octyl phosphate esters andtertiary ruin. containing a heterocyclic nitrogen r in the moleculethereof, are alsoefiective n. suppressors. r instance, the organicammonium octyl phosphate salts prepared from pyridine and al substitutedpyridines, such as the picolines. lutidines, collidines, etc., areuseful anti-foam agents.

For example, pyridine isoamyl octyl phosphate is an excellent foamsuppressor in erai oils and oil compositions. Improved mineral oil sompositions containing this anti-foam agent are specifically claimed inour oopending applies.- tion Serial No. 459,179, filed Sept. 21, 194.2.

The organic ammonium octyl phosphate salts prepared from the methylpyridines. such as picolines, lutidines, etc., are also efiective anti=foam agents. For example, 2,6-dimethyl-pyri-= dine isoamyl octylphosphate is most eflective. Likewise, the other lutidine salts thereofare also excellent anti-foam agents. Improved mineral oil compositionscontaining lutidine isoamyl octyl phosphates, as the anti-foam agent,are specifically claimed in our copending application Serial No.459,180, filed Sept. 21, 194:2.

most efiective.

Again, the monomethyl pyridine salts of isoamyi octyl phosphate andother acid octyl'phosphate esters are good anti-foam agents. In fact,the alpha-picoline salts of isoamyl octyl phosphate anddioctylphosphate, respectively, are Likewise, the beta and gamma picoline saltsof these acid octyl phosphates are good foam inhibitors.

Generically, these addition salts of acid octyl phosphate esters withpyridine and alkyi-pyridines may be represented by the following formulaI wherein R and B, respectively, represent alkyl groups which may besimilar or dissimilar and n is from o to 5. As a class, these salts areuseful and advantageous anti foam agents.

Another advantageous class of antbioam agents is the organic ammoniumoctyl phosphate salts prepared by reacting said acid octyl phosphateesters with other substituted heterocyclic nitrogen losses, such asquinoline, nicotine, eta,

' 1.5.1.. cyclic substituents attached to the spectively, areefiective'foam suppressors.

heterocyclic ring thereof.

n; agents can he prepared from complex nitrogen. bases, as well as fromtertiary amines having a single, simple heterocyclic nitrogen ring.

For example, quinoline isoamyl octyl phosphate is an excellent foaminhibitor. Improved mineral oil compositions containing this anti-foamagent are specifically claimed in our copending application Serial No.454,460, filed August 11, 1942.

Another advantageous anti-f agent is quinoline dioctyl phosphate.Likewise, the quincline salts of other acid octyl phosphate esters arealso efiective foam inhibitors. As a, class, these wherein R representsan alkyl group.

In other words, the heterocyclic nitrogen ring in our organic ammoniumoctyl phosphate salts may be further substituted; even with complexsubstituents such as cyclic groups, as well as simpie methyl or alkylgroups as shown ante.

For instance, the nicotine salts of these acid octyl phosphate estersare also useful anti-foam agents. For example, the nicotine salts ofisoamyl octyl phosphate and diocty1 phosphatei gei a is, our anti-foamagents can also be prepared from complex heterocyclic nitrogen basescontaming a plurality of heterocyclic nitrogen rings.

In this'way, complex Organic ammonium octyl phosphate salts areobtained.

'35 Generically, these addition salts of acid octyl That is, usefulanti-.

phosphate esters with heterocyclic nitrogen bases may be represented bythe following formula:

taining a heterocyclic nitrogen ring, are useful anti-foam agents. Theymay be employed with advantage in the practice of the present invention;this application being a continuation-inpart of said application SerialNo. 454,460, as well as our prior applications Serial Nos. 459,179

and 459,180.

As shown in our Serial No. 453,458 and other prior copendingapplications, these anti-foam agents are quite different from the agentsor ad- I ditives previously employed in mineral oils and oilcompositions. In general, as there stated, dis

solving almost any additive in oil has a tendency to increase foamingmore or less.

On the other hand, our new agents or compounds are remarkable in thatthey suppress foaming, even when present in small amounts, say 0.01 to1.0 per cent by weight of the composition, They have no deleteriouseffect on the lubricating or other properties of the oil.

Our agents can be incorporated in all sorts of oils, to achieve thestated results. One particularly advantageous field of use is in gearlubricants'for automobiles and the like. As stated, these lubricants areviscous and they contain extreme pressure agents or other additives;both of which facts make for heavy foaming. By dissolving a fraction ofa per cent of our agent in such lubricants, foaming is prevented. Forexample, such a gear lubricant, within the purview of our invention, hasthe following compositions (per cent by weight) Refined high-viscosity,lubricating 4 oil 89 to 95.0 Refined sulfurized sperm oil. 5to10.0Dimethylaniline dloctyl phosphate 0.01to 1.0

In the above compositiomany of the organic ammonlum octyl phosphatesdescribed ante may be used, in lieu of dimethylamine dloctyl phosphate,as the anti-foam agent to obtain other advantageous gear lubricants.

Another field of use is in light (low viscosity) oils used in so-calledfluid drives or in hydraulic drives. With these light oils (which areoften of viscosity as low as SAE grade) agitation may produceconsiderable foam, even though the foam subsides very quickly on ceasingagitation. Our new agents are also useful in cutting oils and indeed inany oil or oily composition, whether used as a lubricant or not. inwhich it is desire to prevent foaming.

The proportion of anti-foam agent to be dis solved in the oil or oilbase depends on the viscosity of the oil, its ingredients and severityof the conditions of use. Ordinarily, 0.01 to 1.0 per cent of theseagents by weight on.,the oil'are employed; these organic ammonium octylphosphate salts being very effective agents for the present purposes.

Our new agents can be'readily prepared from various acid octyl phosphateesters and hetero- In one advantageous method ofpreparing these agents,the selected amine and acid octyl phosphate ester are reacted togetherto obtain an organic ammonium phosphate salt thereof; the reactionmixture being. adjusted within the pH range of 2.0 to 5.5 in sopreparing and recovering the amine salt. For example, dimethylaniline isbrought into reaction with isoamyl octyl acid ortho-phosphate, and thepH of the reaction mixture is adjusted to within the range 2 to 4. Withtheoretical molecular ratio of the two reactants 1:1, the product is aptto be slightly too acid, with a pH below 2, and this is taken care of byusing a slight excess of dimethylaniline so that the molecular ratio isbetween 1:1 and 1:1.1. Other useful anti-foam agents can be prepared ina similar manner by reacting various acid octyl phosphates withdimethylaniline or other tertiary amines of the classes described ante,to obtain organic ammonium salts thereof.

In general, the reaction products so obtained are oily materials whichare readily soluble in oils. 'I'hus, dissolving them in oils and oilcompositions is very simple. As they readily dissolve in oils and oilcompositions, our new agents can be easily incorporated and blended inmineral lubricating oils and oil compositions, particularly in theproportions described ante.

Many of the organic ammonium salts of acid octyl phosphate esters whichare disclosed herein are new chemical compounds. The dialkyl aryl aminesalts of isoamyl octyl phosphate are claimed as new chemical compoundsin our copending application, Serial No. 639,701, filed on January 7,1946.. The tertiary heterocyclic nitrogen base salts of isoamyl octylphosphate are in it was dissolved 0.04 per cent of dimethylani linedloctyl phosphate; this anti-foam agent having the following formula andbeing an addition salt of dimethylaniline and acid dloctyl phosphate.

To evaluate the foaming properties of the straight oil and the improvedoil samples (500 cc.) of the two oils were subjected to foam test No. 1(described post). The results were as follows:

Composition Straight oil Improved oil End of stirring (15 minutes):

Temperature, F 84 81 Oil foam, co l, 700 52) Re 0 of volume of oil+ioamto the volume of the original 011.... 3.40 1.04 After 1 hr. standing:

Temperature, F 77 77 Oil f cc 600 500 Ba 0 of volume of oil+ioam to thevolume of the original 11 1. a2 1.0 Nature of foam. Fine No foam It willbe observed that the improved. oil composition so prepared has markedresistance to foaming as compared to the straight oil.

and being an addition salt of dimethylaniiineand acid isoamyl octylorthophosphate.

I As shown in the following table, the change in a viscosity and incolor by incorporation of the agent was negligible.

Straight oil Improved oil Gravity, API 26. 6 28. Viscosity SUV:

100 r 1',e1s 1, 005

Color, NPA f. 75 4. 75

To evaluate the foaming properties of the straight oil and the improved011, samples (500 cc.) of the two Oils were subjected to foam test No. 1(described post). The results were as follows:

Composition Straight'oil Improved oil End of stirring (15 minutes):

Temperature, 84 83 Oil foam, cc.. 1, 740 540 Rat o of volume of oil+ioamto the I volume of the original oil. 3. 48 1. 08 After 1 hr standing:-

Tem ture, F.-. 77 77 0il+foam, cc -a--- 660 500 Ratio of volume ofoil+foam to the volume of the original oil.-- ,1. 32, 120 Nature offoam. Fine. N0 foam It will be noted that the straight oil developed 7more than twice its volume of foam under the conditions of the test andthat an appreciable volume of foam remainedeven after an hour'sstanding; while the improved oil developed only a. negligible amount offoam, which was all gone at the end of an hour.

Decreasing the percentage to 0.01 still leaves the oil muchlesssusceptible' to foaming than the straight oil.

This foam suppressor as stated can be added to compounded lubricants toprevent, foaming thereof. It is compatible with most of the other typesof improvement agents now employed and the amount required to preventfoaming in such compounded lubricants is relatively small and pressor,such compounded lubricants become very resistant to foaming, even underdrastic service conditions.

. In making up compounded lubricants Of this type it is advantageous todissolve the aminophosphate in the oil first, as thereby foaming isprevented during the step of mixing in the extreme pressure agent orother additive. But so far as performance of the lubricant in service isconcerned, the order of addition makes no difference.

The following example illustrates the properties of an extreme pressuregear lubricant prepared in' accordance with the invention.

Example III.-A conventional gear lubricant contains 92.5 per cent byvolume of a highly refined, viscous Pennsylvania 011 and 7.5 per cent ofrefined sulfurized sperm 011 (Smith and Cantrell Patent 2,179,064). Asimilar lubricant prepared according to the invention contains theseoils in proportions 92.46 and 7.5 per cent respectively and'0.04 percent of dimethylaniline salt of acid isoamyl octyl phosphate; thisanti-foam agent being the same as employed in Example II ante.

The viscosity of the conventional lubricant was 1918 SUV at F., 767 atF., and 141.7 at 210 F. The viscosity of the improved lubricant was onlynegligibly different from this, and the same was true of the othercharacteristicsgravity, viscosity index, flash and fire tests, pourtest, color, sulfur, copper strip tests, centrifuge test (forgravity-separable matter), and carbon residue. The neutralization numberof the new lubricant was 0.56 against 0.50 for the old. The surfacetensions were nearly identical. The Almen and Timken tests, indicativeof'the lubricating value of the oil, as secured on the compounded oilbefore the addition of the foam suppressing agent, were the same as thecorresponding tests made after the addition ofthe indicated amount ofthis foam suppressor.

In other words, the characteristics of the two lubricants werepractically the same, except for the foaming properties. The followingare comparable tests (the nature of which is described in detail below)on these properties. The 55 samples were 500 cc. each, the speed of theagitators 550 R. P. M. and the initial temperature r Foam tests g g;Nearlubricant Aiteratirringior 15min... 15min... 44hr.

Temperature, 4 83 83. gil -i-fen n c mur. 1,740.... 540 590. MWMYJT Ws.4s-.--. 1.os..--- 1.16.

S n irring "835: I B I 8 onfiaim miYfitirtlnlfffizz: o

To evaluate the foaming tendency of petroleum oils and compositions atest was devised which aflords an exceptionally accurate indication ofthe comparative foaming tendencies. A sample of oil is subjected to verydrastic foaming conditions under a standardized procedure which makes itpossible to determine quantitatively the tendency of the oil to foam andthe stability or permanency of the foam produced.

In, general it resembles a somewhat similar testing method employed bythe General Motors Corporation for determining the foaming tendencies ofgearing lubricants, but has been modified in the direction of greateraccuracy and in order to make it possible to record more comprehensibletest data.

Foaming' test (No. 1)

the speed of agitation or the time of agitation,

pioyed in the test is the usual household model with two slight changes:the turntable of the usual household mixer is replaced by a rigidplatform, and a cylindrical brass container having an inside diameter of7 inches and an inside height of e'inches is substituted for the usualhousehold glass mixing bowl. The container is fitted with a gageformeasuring the depth of oil or oil and foam therein before and after aii tation.

The agitator device itself comprises a pair of motor driven beaterswhich are of the convex outside surface type as described in U. 8.Patent 2,161,881, each beater having a pair of blades of the typeindicated and being so positioned with respect to each other that thetwo pairs of beater elements are at right angles and rotate in oppositedirections in closely spaced, overlapping paths. In operating position,the heaters are perpendicular to the base of the mixer, as shown inPatent 2,161,881. In the presentjest they are centeredin the containerand the bottom of the heaters is spaced approximately inch from thebottom of the pan when the latter is positioned on the rigid platform.With 500 cc. of oil in the container, the heaters are submerged in theinitial oil sample only to a depth of A of one inch. The heaters arerotated at a speed of 550 R. P. M. controlled within :10 R. P. M.

A measured sample of .500 cc. (:5 cc.) of oil is introduced into thecontainer, the temperature of the sample is brought to 77 F. and the orby taking the final measurements at an earlier or later period. However,in the test referred to in the specific examples ante, the procedurewas.

precisely as indicated.

Test No. 2 is the same as test No. 1 except that agitation is continuedfor 44 hours instead of 15 minutes. (Longer periods of agitation maybeemployed if a still more drastic test is required.)

In some very low viscosity oils considerable foam may develop duringagitation, which disappears very quickly when agitation is stopped.These conditions are found, for example, in marine turbine lubricationsystems (which use light oils) at the point where returned oil isdischarged violently into a reservoir. To evaluate foaming in such casesthere is employed a third test No. 8, similar in all respect to test No.1, except that the measurements of oil and foam are made while the motoris still running. The following example shows how a turbine'oil treatedaccording to the invention behaves under such conditions.

Example IV.--A highly refined Pennsylvania turbine oil was subjected totest No. 3. After 15 minutes agitation on oil plus foam measured 830 cc.as compared with 500 cc. for the original 0 v The same oil aftertreating with 0.01 per cent of dimethylaniline isoamyl octyl phosphatetested only 540 cc. for the oil plus foam.

In the foregoing Examples II, III and IV, we-

- have illustrated certain embodiments of our in- V for thepresentpurposes. The amine salts so container is then placed in positionand the beatto the heaters is permitted to-drain into the con-- tainer,which takes one or two minutes. The foam level is then immediatelydetermined. and the temperature of the sample is measured. It is thenpossible to calculate the ratio of the volume of oil and foam to thevolume of the original oil, with correction for any temperature changes.

The container is removed and allowed to 'stand quiet for one hour(measured from the time the stirring is stopped). The volume andtemperature measurements are taken again, and serve to indicatestability or permanence of the foam produced.

Ofcoursa-the test procedure may be varied, as for-example by changingthe size of the sample,

obtained may be used in lieu of the dimethylaniline isoamyl octylphosphate in the examples given ante. Such additional embodiments of ourinvention are further illustrated in the examples "given post, whichillustrate other advantageous ways of practicing this invention.

Example V.-Another improved gear lubricant was prepared as follows: Ahighly viscous, highly refined Pennsylvania oil was selected as the baseand in it was dissolved 0.04; per cent of pyridine isoamyl octylphosphate; this anti-foam agent having the following formula:

and being an addition salt of pyridine and acid isoamyl octyl phosphate.

The foaming properties of the straight oil and the improved oil, asmeasured by foam test No. 1, were as follows:

accuser proved gear lubricants in accordance with this invention, asillustrated in the follo example: Y I

Example VII.-A highly viscous highly refined Pennsylvania oil wasselected as the base and in it was dissolved 0.04 per centof quinolineisoamyl octyl phosphate; this antiloam agent having the followingformula volume 0! original oil ltwill be noted that the straight alldeveloped morethan twice its volume of foam and that an appreciablevolume of foam remained even after one hour standing while the improvedoil developed only a negligible amount of foam which was all gone at theend 0! an hour.

In the above example, decreasing the percent M age of anti-foam agent to0.01 per cent still leaves the oil much less susceptibleto foaming thanthe straight oil. Thatis, pyridine isoamyl ootylphosphat/e is a veryefiective foam inhibitor. Accordingly, it is also useful andadvantageous, as a foam suppressonin compounded gear lubricants and inturbine oils such as shown in Examples and IV ante. In fact, as shown byvarious roam tests, pyridine isoamyl octyl phosphate also efiectivelysuppresses foaming in such compositions.

Further, in such compositions, other addition salts oi acid isoamyloctyl phosphate and pyridine compounds containing substituent groupsattached to the pyridine ring thereof, may be used as the anti-foamagent. The improved oil compositions so obtained are also advantageousin the practice of this invention.

Typical examples of these advantageous compositions are as follows:

Example VI.-A highly refined Pennsylvania turbine oil was subjected totest No. 3. After 15 minutes agitation, the 011 plus foam measured 800cc. as compared with 500 cc. for the original oil. The same oil aftertreating with 0.01 per cent or 2,6-lutidine isoamyl octyl phosphateshowed only 540 cc. of oil plus foam.

This advantageous -anti=foam inhi itor has the following formula poundsso obtained are likewise excellent foam suppressors. They may also beemployed in making improved lubricantssimilar to those illustratedin'the example ante. Further, the octyl phosphate salts of othersubstituted pyridine compounds are also useful anti-foam agents. For

instance, they are advantageous in preparing imand being an additionsalt of quinoline and acid isoamyl octyl phosphate.

The foaming properties of the straight oil. and the improved oil, asmeasured as foam test No. l were as follows:

Composition Straight oil Improved oil At end 0! stirring (15 minutes):

Temperature, 83 Volume of oil and foam, cc. 1, 756 540 Bet l 3. 1.08After 1 hr. standing:

Temperature, F 77 77 Volume of oil and foam. cc 070 500 Retio l. 34 1.0Nature Fine No foam volume of oil and foam. volume oi original oil Itwill be observed that the straight oil developed more than twice itsvolume of foam under the conditions of the test and that an appreciablevolume of foam remained even after one hour's standing, while theimproved oil developed only a negligible amount of foam, which was allgone at the end of one hour.

In the above example, the addition salts of other acid octyl phosphateesters, such as dioctyl phosphate etc. etc., with quinoline may also beused as the anti-foam agent to produce still other advantageous gearlubricants. likewise, the salts of acid octyl phosphate esters withother 1 Ratio of complex heterocyclic nitrogen bases may be used inmaking such lubricants. For instance, nico= tine isoamyl octyl phosphatemay be employed gear lubricants as illustrated m the iollowiu example.

. Example VIM-Another improved gear lubricant made according, to thisinvention was prepared by incorporating 0.04 per cent of nicotineisoamyl octyl phosphate in a modern commercial gear lubricant containing92.0 per cent by volume or highly refined viscous Pennsylvania 011 and8.0 per cent or a special synthetic mixture containing around 10 percent-o1 sulfun.

The viscosity of the .improved lubricant was I only negligibly diflerentfrom the original'o l.

and the same was true of the other characteristics-gravity, viscosityindex, flash and the tests, pour test, color, sulfur,- copper striptests.

centrifuge test (for gravity-separable matter) and carbon residue. Theneutralization number oi the improved lubricant was 0.45 compared to0.42 tor the old. The surface tension were seams:

nearly identical. The Almen and 'Iimken tests, indicative of thelubricating value of the oil, as secured on the compounded oil beforethe addition of the foam suppressing agent, were the same as thecorresponding tests made after the addition of the indicated amount ofthis foam suppressor.

In other words, the characteristics of the two lubricants werepractically the same except for the-roaming properties winch were asfollows:

Foam tests New lubricant After stirring for 15 min i 15 min 44hr.Temperature, F M 83 V 83. Oil+ioam, cc 1,750.. 540 590. Ratio ofvolumeqi oil+ioam to 3.49"... 1.08 1.18.

the volume of original oil. After 1 hr. standing:

Temperature, F 77 77 77. il+ioam, cc 665 500 500. Ratio of volume ofoil+ioam to 1.33. 1.00..... 1.00.

the volume of the original oil. Nature of foam Fine. None None.

In the above test, the samples were 500 cc. each, the speed of theagitators 550 R. P. M. and the temperature 77 F.

Likewise, the addition salts of other complex heterocyclic nitrogenbases may be employed in the above example as the foam agent in lieu ofnicotine isoamyl octyl phosphate.

That is, as shown in the foregoing specific examples, the addition saltsof acid isoamyl octyl phosphate with sisting of dialkylaryl amines andheterocyclic nitrogen bases, are effective foam suppressors and areuseful in many embodiments of our invention. Likewise, as stated ante,the addition salts of these amines with dioctyl phosphate and other acidoctyl phosphate esters are also effective antitertiary amines of theclass con-;

foam agents and may be employed in any of the foregoing examples toobtain improved oil compositions resistant to foaming.

Thus, in the general practice of our invention, a wide variety oforganic ammonium octyl phosphate salts, within the broad class definedherein,

may be employed to prevent or suppress the foaming of mineral oils andoil compositions. As a class, our new anti-foam agents are readilysoluble in mineral oils and lubricants and are excellent !oamsuppressors. Their use in mineral lubricating oils and compoundedlubricants has been fully illustrated ante.

While our invention has been described above with reference to specificexamples and embodiments, it will be understood that the invention isnot limited to such illustrative examples and embodiments but may bevariously practiced within the scope of the claims herein made.

What we claim is:

1. A mineral oil composition resistant to foaming, comprising mineraloil and a small proportion of nicotine isoamyl octyl phosphate, theproportion of nicotine isoamyl octyl phosphate being sufiicient toovercome the normal roaming tendency of the mineral oil and to suppressthe foaming of the oil composition when agitated under serviceconditions.

2. As an improvement in suppressing the foaming of mineral oils and oilcompositions when agitated in the presence of air and other gases, theimprovement which comprises maintaining from 0.01 to 1.0 per cent byweight of nicotine isoamyl octyl phosphate dissolved in the oil whilebein so agitated, the amount of nicotine isoamyl octyl phosphate beingsufilcient to suppress foaming of the oil composition during suchagitation.

" HERSCHEL G. SMITH. TROY L. CAN'I'RELL.

